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| United States Patent |
5,131,827
|
|
Tasaka
|
July 21, 1992
|
Fiber- and whisker-reinforced injection moldable resin composition for
scroll compressor parts and method of manufacturing scroll compressor
parts
Abstract
This invention relates to a resin composition for scroll compressor parts
which comprises
(A) about 40 to 70 parts by weight of at least one thermoplastic resin
selected from the group consisting of polyphenylene sulfide,
polyetheretherketone, polyetherketone, all-aromatic polyester, nylon-4,6,
nylon-MXD6, polysulfone, polyarylsulfone, polyethersulfone,
polyetherimide, polyamide-imide and polyimide,
(B) about 15 to 45 parts by weight of whisker with an average fiber
diameter of not more than about 3 .mu.m and a tensile modulus of not less
than about 10,000 kgf/mm.sup.2 ;
(C) about 10 to 25 parts by weight of heat-resistant fiber with an average
fiber diameter of not more than about 30 .mu.m and a tensile modulus of
not less than about 6,500 kgf/mm.sup.2 ; and
(D) about 5 to 20 parts by weight of a finely divided solid lubricant, the
sum total of components (A) to (D) being 100 parts by weight and a method
of manufacturing scroll compressor parts characterized in that the above
composition is injection molded.
| Inventors:
|
Tasaka; Takio (Tokushima, JP)
|
| Assignee:
|
Otsuka Kagaku Kabushiki Kaisha (Osaka, JP)
|
| Appl. No.:
|
607774 |
| Filed:
|
October 31, 1990 |
Foreign Application Priority Data
| May 29, 1987[JP] | 62-136518 |
| Current U.S. Class: |
418/55.2; 264/275; 264/328.1; 264/328.18; 418/56; 524/75; 524/76; 524/404; 524/406; 524/592; 524/601; 524/606; 524/609 |
| Intern'l Class: |
F04D 007/02; B29C 045/03; C08J 005/10 |
| Field of Search: |
264/331.12,331.16,331.19,328.18,275,328.1
524/592,601,606,609,75,76,404,406
418/55.2,56
|
References Cited
U.S. Patent Documents
| 4599383 | Jul., 1986 | Satoji | 524/495.
|
| 4755585 | Jul., 1988 | Hanson et al. | 524/600.
|
| 4760109 | Jul., 1988 | Chiba | 524/606.
|
| 4772422 | Sep., 1988 | Hijikata et al. | 524/601.
|
| 4777204 | Oct., 1988 | Ikenaga et al. | 264/331.
|
| Foreign Patent Documents |
| 55-7848 | Jan., 1980 | JP.
| |
| 55-21283 | Feb., 1980 | JP.
| |
| 57-13586 | Mar., 1982 | JP.
| |
| 58-127761 | Jul., 1983 | JP.
| |
| 59-179656 | Oct., 1984 | JP.
| |
| 59-179659 | Oct., 1984 | JP.
| |
| 59-182842 | Oct., 1984 | JP.
| |
| 60-228558 | Nov., 1985 | JP.
| |
| 61-185566 | Aug., 1986 | JP.
| |
| 61-190557 | Aug., 1986 | JP.
| |
| 62-43459 | Feb., 1987 | JP.
| |
Primary Examiner: Lowe; James
Attorney, Agent or Firm: Armstrong & Kubovcik
Parent Case Text
This application is a continuation of application Ser. No. 340,095 filed as
PCT/JP88/00477, May 20, 1988 and now abandoned.
Claims
I claim:
1. A resin composition for scroll compressor parts which consists
essentially of
(A) about 40 to 63 parts by weight of at least one thermoplastic resin
selected from the group consisting of polyphenylene sulfide,
polyether-etherketone, polyetherketone, all-aromatic polyester, nylon-4,6,
nylon-MXD6, polysulfone, polyarylsulfone, polyethersulfone,
polyetherimide, polyamide-imide and polyimide;
(B) about 15 to 45 parts weight of whisker with an average diameter of not
more than about 3 .mu.m and a tensile modulus of not less than about
10,000 kgf/mm.sup.2, said whisker being at least one selected from the
group consisting of potassium titanate whisker, silicon carbide whisker,
carbon graphite whisker, silicon nitride whisker and .alpha.-alumina
whisker;
(C) about 10 to 25 parts by weight of heat-resistant fiber with an average
fiber diameter of not more than about 30 .mu.m and a tensile modulus of
not less than about 6,500 kgf/mm.sup.2 ; and
(D) about 5 to 20 parts by weight of a finely divided solid lubricant, said
finely divided solid lubricant being at least one selected from the group
consisting of polytetrafluoroethylene, ultra-high molecular weight
polyethylene, all-aromatic polyamide, microfine phenolic resin, molybdenum
disulfide, tungsten disulfide, WSe.sub.2, MoSe.sub.2 and boron nitride,
the sum total of components (A) to (D) being 100 parts by weight.
2. The composition of claim 1 wherein said thermoplastic resin has a
deflexion temperature (ASTM D648, 1. 86MPa) of not less than 150.degree.
C. and an UL temperature index (UL746) of not less than 120.degree. C.
3. The composition of claim 1 wherein said thermoplastic resin is
polyphenylene sulfide, polyetheretherketone, all-aromatic (thermotropic
liquid crystal) polyester, polyethersulfone or polyether imide.
4. The composition of claim 1 wherein said thermoplastic resin is used in
an amount of about 45 to 63 parts per 100 parts by weight of the
composition.
5. The composition of claim 1 wherein said whisker is at least one member
selected from the group consisting of potassium titanate whisker, silicon
carbide whisker, carbon graphite whisker, silicon nitride whisker and
.alpha.-alumina whisker, which has an average fiber diameter of about 0.1
to 3 .mu.m and a tensile modulus of not less than about 10,000
kfg/mm.sup.2.
6. The composition of claim 1 wherein said whisker is used in an amount of
about 20 to 35 parts by weight per 100 parts by weight of the composition.
7. The composition of claim 1 wherein said heat-resistant fiber is at least
one member selected from the group consisting of carbon fiber, alumina
fiber, zirconia fiber, silicon carbide fiber, silica fiber, glass fiber
and aromatic polyamide fiber, which has an average fiber diameter of about
0.5 to 30 .mu.m, an average fiber length of about 0.5 to 6 mm, and a
tensile modulus of not less than about 6,500 kgf/mm.sup.2.
8. The composition of claim 7 wherein said heat-resistant fiber is alumina
fiber, silicon carbide fiber or carbon fiber, which has a tensile modulus
of not less than 15,000 kgf/mm.sup.2.
9. The composition of claim 1 wherein said heat-resistant fiber is used in
an amount of about 10 to 20 parts by weight per 100 parts by weight of the
composition.
10. The composition of claim 1 wherein said finely divided solid lubricant
has an average particle diameter of about 0.5 to 100 .mu.m.
11. The composition of claim 1 wherein said finely divided solid lubricant
is used in an amount of about 7 to 15 parts by weight per 100 parts by
weight of the composition.
12. The composition of claim 1, wherein said whisker has a diameter in the
range of about 0.1 .mu.m to about 3 .mu.m, and said fiber has a diameter
in the range of about 0.5 .mu.m to about 30 .mu.m.
13. A method of manufacturing scroll compressor parts comprising the step
of injection-molding a resin composition for scroll compressor parts which
consists essentially of
(A) about 40 to 63 parts by weight of at least one thermoplastic resin
selected from the group consisting of polyphenylene sulfide,
polyether-etherketone, polyetherketone, all-aromatic polyester, nylon-4,6,
nylon-MXD6, polysulfone, polyarylsulfone, polyethersulfone,
polyetherimide, polyamide-imide and polyimide;
(B) about 15 to 45 parts by weight of whisker with an average diameter of
not more than about 3 .mu.m and a tensile modulus of not less than about
10,000 kgf/mm.sup.2, said whisker being at least one selected from the
group consisting of potassium titanate whisker, silicon carbide whisker,
carbon graphite whisker, silicon nitride whisker and .alpha.-alumina
whisker;
(C) about 10 to 25 parts by weight of heat-resistant fiber with an average
fiber diameter of not more than about 30 .mu.m and a tensile modulus of
not less than about 6,500 kgf/mm.sup.2 ; and
(D) about 5 to 20 parts by weight of a finely divided solid lubricant, said
finely divided solid lubricant being at least one selected form the group
consisting of polytetrafluoroethylene, ultra-high molecular weight
polyethylene, all-aromatic polyamide, microfine phenolic resin, molybdenum
disulfide, tungsten disulfide, WSe.sub.2, MoSe.sub.2 and boron nitride,
the sum total of components (A) to (D) being 100 parts by weight.
14. The method of claim 13 wherein injecting molding is carried out using
an insert of metallic material which is capable of imparting rigidity to
the resulting scroll compressor parts.
15. The method of claim 13, wherein said whisker has a diameter in the
range of about 0.1 .mu.m to about 3 .mu.m, and said fiber has a diameter
in the range of about 0.5 .mu.m to about 30 .mu.m.
16. A scroll compressor part, which is a fixed scroll, an orbiting scroll,
a drive shaft or an Oldham coupling, manufactured by the method of claim
13.
17. The scroll compressor part of claim 16, wherein said whisker has a
diameter in the range of about 0.1 .mu.m to about 3 .mu.m, and said fiber
has a diameter in the range of about 0.5 .mu.m to about 30 .mu.m.
Description
TECHNICAL FIELD
This invention relates to a resin composition for scroll compressor parts
and a method of manufacturing scroll compressor parts. More particularly,
this invention relates to a resin composition for manufacture of precision
parts of the scroll compressor which is used as an air conditioner
compressor, an air or gas compressor or the like and a method of
manufacturing such parts.
BACKGROUND TECHNOLOGY
The scroll compressor comprises a fixed scroll and an orbiting scroll each
equipped with a mirror plate member and an involute spiral member (called
scroll lap) perpendicular to said mirror plate member, the respective laps
being interleaved in such a manner that one is fixed with the other free
to orbit without spinning about its own axis so as to cause a closed space
defined by and between the scroll laps to be shifted and diminished in the
direction from the outer circumference to the inner circumference to
thereby compress a gas such as Freon gas.
Heretofore, all the fixed scroll and orbiting scroll of the scroll
compressor and the drive shaft (called rotor shaft) for driving the
orbiting scroll have been made of cast iron. However, the scroll laps, the
mirror surface of the mirror plate member and the surface of the rotor
shaft which demand a precision of the order of microns must be subjected
to both rough grinding and finishing which are time-consuming and
extremely poor in production efficiency. In addition, the tools are
subject to wear and require a very complicated tool control for
maintaining the required processing accuracy. Therefore, an attempt was
made to use cast aluminum which is easier to process in lieu of cast iron.
However, in this case, the large centrifugal force accompanying a high
speed gyration causes a large deformation and there is also a constant
risk of general destruction due to an impact caused by local contact, thus
requiring sufficient oil lubrication not only from the standpoint of wear
resistance but also for circumventing the above-mentioned risk. The need
for oil lubrication means that there must be a mechanism for pumping the
lubricating oil, which would add to the complexity of the structure, thus
imposing limitations on the reduction of cost, size and weight of parts.
Furthermore, the metal rotor shaft of cast iron or cast aluminum has the
disadvantage that the transmission magnetic sound (i.e. noise) from the
motor rotor is high and that it is of large weight.
SUMMARY OF THE INVENTION
It is an object of this invention to provide a resin composition from which
precision parts for a scroll compressor can be manufactured by the
high-production technique of injection molding, which parts are
lightweight and of high rigidity, with good dimensional accuracy, high in
heat resistance and serviceable with a minimum of oil lubrication.
It is another object of this invention to provide a method for
manufacturing precision parts of a scroll compressor from said resin
composition.
It is a still another object of this invention to provide scroll compressor
parts as manufactured by the above-mentioned manufacturing method.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a longitudinal sectional elevation view of a scroll compressor.
FIG. 2 is a sectional view of the same scroll compressor taken along the
line I--I' of FIG. 1.
DESCRIPTION OF THE INVENTION
This invention provides a resin composition for scroll compressor parts
which comprises per 100 parts of the composition
(A) about 40 to 70 parts by weight of at least one thermoplastic resin
selected from the group consisting of polyphenylene sulfide,
polyetheretherketone, polyether ketone, all aromatic polyester, nylon-4,6,
nylon-MXD6, polysulfone, polyarylsulfone, polyethersulfone,
polyetherimide, polyamide-imide and polyimide;
(B) about 15 to 45 parts by weight of whiskers with an average fiber
diameter of not more than about 3 .mu.m and a tensile modulus of not less
than about 10,000 kgf/mm.sup.2 ;
(C) about 10 to 25 parts by weight of heat-resistant fiber with an average
fiber diameter of not more than about 30 .mu.m and a tensile modulus of
not less than about 6,500 kgf/mm.sup.2 ; and
(D) about 5 to 20 parts by weight of a finely-divided solid lubricant.
In another aspect, this invention provides a method for manufacturing
scroll compressor parts which is characterized by injection-molding a
resin composition comprising the above-mentioned components (A) to (D).
Furthermore, this invention provides scroll compressor parts as
manufactured by the above manufacturing method.
The above resin composition of this invention, when injection-molded,
provides scroll compressor parts which are lightweight, of high rigidity,
with good dimensional accuracy and high creep- and heat-resistance, and
serviceable with a minimum of oil lubrication. Moreover, with the resin
composition of this invention, scroll compressor parts having necessary
performance characteristics can be manufactured by the advantageous
high-production technique of injection molding without after-processing.
The scroll compressor parts thus manufactured are excellent in dimensional
accuracy and surface smoothness, for instance, and can therefore be used
directly as orbiting scrolls, fixed scrolls or other parts without
necessitating any cutting operation. Particularly the mirror surface of
the mirror plate which is contacted by the scroll lap is very smooth
because of the good mold transferability due to the incorporation of
whiskers and satisfactory in wear resistance because of the incorporation
of said finely divided solid lubricant.
Particularly in accordance with this invention, injection-molding of the
above resin composition provides scroll compressor parts having excellent
properties such as an ASTM D792 specific gravity of about 1.3 to 2.5, an
ASTM D648 deflexion temperature (under a flexural load of 18.6
kgf/cm.sup.2) of not less than 180.degree. C., an ASTM D790 flexural
modulus of not less than 800 kgf/mm.sup.2, a surface roughness of not more
than 5s, and a dynamic friction coefficient of not more than 0.25.
As manufactured in accordance with this invention, the scroll lap and the
surface of the mirror plate contacted thereby are so smooth and high in
lubricity and wear resistance as mentioned above that the hitherto
required embedding of chip seal can now be dispensed with, facilitating
assemblage of the scroll compressor. Furthermore, when the compressor part
according to this invention is a drive shaft, it has the advantage of a
reduced level of gyration sound (noise). In addition, since the scroll
compressor part according to this invention is made of resin, it is not
rusted and because the very material is highly slidable and resistant to
wear, t is very durable, thus being able to replace the corresponding
metal part.
The thermoplastic resin used as component (A) in accordance with this
invention can be any member of a variety of resins only if it is such that
when reinforced by specified amounts of component (B) whisker, component
(C) heat-resistant fiber and component (D) finely divided solid lubricant
to be described hereinafter, it provides a resin molded product having a
deflexion temperature (under a load of 18.6 kgf/cm.sup.2) of not less than
180.degree. C. As such thermoplastic resins, polyphenylene sulfide,
polyetheretherketone, polyetherketone, all-aromatic polyester, nylon-4,6,
nylon-MXD6, polysulfone, polyarylsulfone, polyethersulfone,
polyetherimide, polyamide-imide, polyimide, etc. can be employed and these
resins may be used singly or in combination.
The polyphenylene sulfide mentioned above is a resin having a repeating
unit of the general formula
##STR1##
The polyetheretherketone is a resin having a repeating unit of the general
formula
##STR2##
The polyetherketone is a resin having a repeating unit of the general
formula
##STR3##
The all-aromatic polyester may for example be a polycondensate of mixed
terephthaloyl-isophthaloyl chloride with bisphenol A, which is
commercially available under the tradename of U Polymer (manufactured by
Unitika Ltd.), for instance, or a thermotropic liquid crystal polyester
containing p-hydroxybenzoic acid. As examples of the latter, there may be
mentioned the polycondensate of p-hydroxybenzoic acid,
6-hydroxy-2-naphthalenecarboxylic acid and terephthalic acid, which is
commercially available under the tradename of Vektra (manufactured by
Hoechst-Celanese), for instance, and the polycondensate of
p-hydroxybenzoic acid, 4,4'-biphenol and terephthalic acid, which is
commercially available under the tradename of Ekonol (manufactured by
Sumitomo Chemical Industries, Ltd.) or Xydar (manufactured by Dartco
Manufacturing), for instance. Nylon-4,6 is a resin having a repeating unit
of the general formula
##STR4##
which is available under the tradename of Stanyl (manufactured by DSM).
Nylon-MXD6 is a resin which, for example, has a repeating unit of the
general formula
##STR5##
which is available under the tradename Of RENY (manufactured by Mitsubishi
Gas Chemical), for instance. The polysulfone is exemplified by a resin
having a repeating unit of the general formula
##STR6##
which is available under the tradename of UDEL (manufactured by UCC), for
instance. The polyarylsulfone may for example be a resin having a
repeating unit of the general formula
##STR7##
which is commercially available under the tradename of RADEL (manufactured
by Carborandum), for instance. The polyethersulfone may for example be a
resin containing a repeating unit of the general formula
##STR8##
which is available under the tradename of VICTREX PES (manufactured by
ICI), for instance. The polyetherimide may for example be a resin having a
repeating unit of the general formula
##STR9##
which is commercially available under the tradename of ULTEM (manufactured
by GE), for instance. The polyamide-imide may for example be a resin
having a repeating unit of the general formula
##STR10##
which is available under the tradename of Torlon (manufactured by Amoco),
for instance. The polyimide may for example be a resin containing a
repeating unit of the general formula
##STR11##
and a repeating unit of the general formula
##STR12##
which is commercially available under the tradename of Polyimide 2080
(manufactured by Upjohn), for instance.
If the thermoplastic resin is such that, when compounded and reinforced
with specified amounts of component (B) whisker, component (C)
heat-resistant fiber and component (D) finely divided solid lubricant, it
provides a resin composition with a deflexion temperature of less than
180.degree. C., the heat resistance of the resin composition will be so
undesirably poor that the composition tends to be unable to withstand the
heat which is generated, for instance, by the friction between the scroll
laps under the pressure of, say, freon gas, the friction between the
orbiting scroll and the drive shaft and the friction between the drive
shaft and the bearing.
In this invention, the above-mentioned component (A) thermoplastic resin is
preferably one belonging to the category of heat-resistant engineering
plastics which has (i) a deflexion temperature (ASTM D648, 1.86 MPa) of
not less than 150.degree. C. and (ii) an UL temperature index (UL746) of
not less than 120.degree. C. In this invention, the polyphenylene sulfide,
polyetheretherketone, all-aromatic (thermotropic liquid crystal)
polyester, polyethersulfone and polyetherimide which have the above
properties can be used with particular advantage in terms of moldability,
dimensional stability, mechanical properties and freon resistance.
The component (B) whisker to be employed in this invention may be any of
various whiskers having an average fiber diameter of not more than about 3
.mu.m, particularly about 0.1 to 3 .mu.m, and preferably about 0.1 to 2
.mu.m and a tensile modulus of not less than about 10,000 kgf/mm.sup.2. In
this invention, the potassium titanate whisker, silicon carbide whisker,
carbon graphite whisker, silicon nitride whisker, .alpha.-alumina whisker
etc. which have the average fiber diameter and tensile modulus specified
hereinbefore can be used singly or in combination. Incorporation of the
above whisker not only results in improvements in dimensional accuracy and
surface smoothness of scroll compressor parts but also results in
interfilament reinforcement of component (C) heat-resistant fiber and a
uniform filling thereof into the resin matrix. If the average fiber
diameter of the whisker used exceeds 3 .mu.m, the surface smoothness and
other properties of scroll compressor parts will be undesirably
sacrificed. If the whisker has a tensile modulus below 10,000
kgf/mm.sup.2, it tends to become undesirably difficult to achieve a
rigidity comparable to that of metal by the addition of whisker to the
resin composition. The length of component (B) whisker can be selected
generally from the range of 1 to 1,000 .mu.m and typically from the range
of 10 to 200 .mu.m.
The component (C) heat-resistant fiber to be used in this invention may be
any of various heat-resistant fibers having an average fiber diameter of
not more than about 30 .mu.m, particularly about 0.5 to 30 .mu.m, and
preferably about 0.5 to 20 .mu.m and a tensile modulus of not less than
about 6,500 kgf/mm.sup.2. In this invention, as representative examples of
such heat-resistant fiber, there may be mentioned the carbon fiber,
alumina fiber, zirconia fiber, silicon carbide fiber, silica fiber, glass
fiber, aromatic polyamide fiber such as ARMID, etc. which have the
above-specified average fiber diameter and tensile modulus and these
fibers can be used singly or in combination. The use of such
heat-resistant fiber helps improve the strength, rigidity, impact
resistance, deformation resistance (thermal deformation, creep
characteristic), etc. of the scroll compressor parts molded from the
composition of this invention. If the average fiber diameter of the
heat-resistant fiber exceeds 30 .mu.m, it tends to become difficult to
control the surface roughness below 5s, the level necessary for scroll
compressor parts, even with the aid of said whisker. If the tensile
modulus is below 6,5000 kgf/mm.sup.2, the tendency arises that the
flexural modulus of the parts obtained by the injection molding of the
scroll compressor part resin composition of this invention is hard to
attain a minimum of 800 kgf/mm.sup.2 which is necessary for the parts to
substitute the metal counterparts. Particularly beneficial are the alumina
fiber, silicon carbide fiber and carbon fiber with a tensile moduls of not
less than about 15,000 kgf/mm.sup.2 and preferably not less than about
20,000 kgf/mm.sup.2, and of these fibers, the high-strength or
high-modulus carbon fiber of the PAN type is the most desirable. However,
for the production of pellets of the composition of this invention which
is described hereinafter and in terms of injection moldability, these
heat-resistant fibers are preferably used in the form of cut fibers with a
fiber length of about 0.5 to 6 mm.
The component (D) finely divided solid lubricant to be used in this
invention may be any of various lubricants, for example at least one
member selected from the group consisting of polytetrafluoroethylene
(particularly one with an average molecular weight of about a few thousand
to 300 thousand), high-density polyethylene (particularly one with a
density of about 0.945 to 0.970 and a viscosity average molecular weight
of about 10 thousand to 400 thousand), ultra-high molecular weight
polyethylene (particularly one with a viscosity average molecular weight
of about 500 thousand to 5 million), all-aromatic polyamide powder such as
polyphenyleneisophthalamide, ultramicrofine phenol resin (particularly one
with a bulk density of 0.3 to 0.8 g/cc; tradename "Bellpearl", product of
Kanebo, Inc.), and its graphitizate (for example, Bellpearl C-600, product
of Kanebo, Inc.), graphite, molybdenum disulfide, tungsten disulfide,
WSe.sub.2 MoSe.sub.2 and boron nitride. The average particle diameter of
these lubricants is not more than 100 .mu.m, particularly about 0.5 to 100
.mu.m and preferably about 1 to 30 .mu.m. The incorporation of such a
finely divided solid lubricant remarkably improves the wear resistance of
scroll compressor parts. The use of a finely divided solid lubricant with
an average particle diameter in excess of 100 .mu.m would tend to
adversely affect the surface smoothness of scroll compressor parts.
In the practice of this invention, it is important that the above-mentioned
components be compounded in the proportions indicated below.
Thus, the proportion of the thermoplastic resin constituting said component
(A) is about 40 to 70 parts and preferably about 45 to 63 parts per 100
parts of the composition of this invention. (All parts are by weight; the
same applies hereinafter.) If the proportion of the thermoplastic resin is
less than 40 parts, the resulting resin composition will suffer from
disadvantages in regard to injection moldability and the injection-molded
scroll compressor parts will tend to become undesirably brittle. On the
other hand, if the proportion of the thermoplastic resin exceeds 70 parts,
the flexural modulus of parts molded from the resulting resin composition
will not reach 800 kgf/mm.sup.2 and the parts may undesirably deform at a
high pressure, for example, of freon gas. Such parts are only usable for
compressors operated with a small amount of refrigerant.
The whisker constituting said component (B) is incorporated in a proportion
of about 15 to 45 parts and preferably about 20 to 35 parts per 100 parts
of the composition of this invention. If the proportion of whisker is less
than 15 parts, the beneficial effect of addition of whisker (especially
improvements in surface smoothness and dimensional accuracy) will tend to
be scarcely developed. The use of whisker in a proportion of more than 45
parts results in a relative decrease in the amount of thermoplastic resin,
heat-resistant fiber and finely divided solid lubricant, so that the
desired effects of the invention may not be achieved.
The heat-resistant fiber constituting said component (C) is used in a
proportion of about 10 to 25 parts and preferably about 10 to 20 parts per
100 parts of the composition of this invention. If the proportion of
heat-resistant fiber is less than 10 parts, the desired effect of addition
of heat-resistant fiber (particularly, improved impact resistance) may
hardly come by. If the proportion of heat-resistant fiber exceeds 25
parts, it will become difficult to control the surface roughness below 5s
which is required for the sliding surfaces of scroll compressor parts.
The finely divided solid lubricant constituting said component (D) is used
in a proportion of about 5 to 20 parts and preferably about 7 to 15 parts
per 100 parts of the composition of this invention. If the proportion of
finely divided solid lubricant is less than 5 parts, the effect of
addition of such finely divided solid lubricant may undesirably be
scarcely realized. On the contrary, if the proportion of solid lubricant
exceeds 20 parts, the undesirable tendency will arise that the strength of
scroll compressor parts is drastically reduced.
In the resin composition of this invention, within the range that its
fundamental physical characteristics, moldability, etc. are not adversely
affected, said whisker or heat-resistant fiber may be partially replaced
with inorganic fillers such as talc, mica, silica, etc. or, for increasing
the surface hardness, with metal whiskers and/or powders of metals such as
brass, zinc, and so on. Depending on cases, it is also possible to
incorporate carbon black, colorants such as inorganic or organic pigments,
heat stabilizers and so on.
For the production of the resin composition of this invention, there may be
employed, for example, the method which comprises weighing the necessary
amounts of said thermoplastic resin, whisker, heat-resistant fiber and
finely divided solid lubricant, blending them evenly in a blender such as
a tumbler mixer, kneading the same in a melt kneader such as an extrusion
machine and pelletting the same to provide the composition in the form of
pellets.
The specific gravity of the resin composition of this invention is usually
in the range of 1.3 to 2.0. However, when high-specific-gravity alumina
whisker, zirconia fiber, metal whisker or metal powder is used
concomitantly, the specific gravity may be as high as 2.5 at the maximum.
Scroll compressor parts can be manufactured by injection-molding the above
resin composition. For example, a metal mold for the desired scroll
compressor part (one cavity metal mold for the orbiting scroll, fixed
scroll or drive shaft) is set on a precision injection molding machine and
the machine is set to the predetermined values of cylinder temperature,
mold temperature, injection pressure and injection time, suitable for
molding the thermoplastic resin used. Then, the machine is started to
manufacture the desired part.
In the manufacture of scroll compressor parts according to this invention,
it is possible to employ a metal insert such as one made of cast aluminum,
cast iron or the like for imparting added rigidity to the scroll lap or
drive shaft.
EXAMPLES
This invention is described in further detail below by way of example. It
should be understood that the examples given are merely illustrative of
the invention and should by no means be construed to be limitative of the
scope of the invention. The component (A) thermoplastic resins used in the
examples and comparative examples are invariably those having a deflexion
temperature (ASTM D648, 1.86 MPa) of not less than 150.degree. C. and an
UL temperature index (UL746) of not less than 120.degree. C.
EXAMPLES 1 TO 4 AND COMPARATIVE EXAMPLES 1 AND 2
Using a blender, the respective components were blended in the proportions
(parts by weight) indicated in Table 1. The resulting compound was
melt-kneaded in a 45 mm extruder at a cylinder temperature of 300 .degree.
C. and pelletted with a cutter. Using the resulting pellets, a fixed
scroll and an orbiting scroll were respectively injection-molded at a
cylinder temperature of 320.degree. C., a mold temperature of 120.degree.
C., an injection pressure (primary pressure) of 1,200 kgf/cm.sup.2 and a
hold pressure (secondary pressure) of 650 kgf/cm.sup.2.
To examine the fundamental physical properties of the same material, the
following specimens were prepared using the ASTM mold for test specimens
under the same conditions as above and each specimen was allowed to stand
in a constant temperature-humidity chamber maintained at 20.degree. C. and
50% RH for 24 hours and evaluated for the following physical properties.
The results are given below in Table 2.
Specific gravity: ASTM D792; measured using Izod impact test specimen.
Flexural modulus: ASTM D790; thickness 6.4 mm, width 12.7 mm, rate of
crosshead motion 5 mm/min.
Deflexion temperature: ASTM D648; the same test specimen as above was
subjected to the test under a load of 18.6 kgf/cm.sup.2.
Sliding characteristic: Suzuki type frictional wear tester [EFM-III-EN,
manufactured by Toyo Baldwin], thrust wear between parts of the same
material (surface roughness, Ra=0.2-0.3 .mu.m, Rz=1.0-2.5 .mu.m),
measuring load 3 kgf/cm.sup.2, peripheral speed 30 cm/sec., distance of
travel 10 Km.
Izod impact: ASTM D256; width 6.6 mm (1/4 inches), thickness 12.7 mm, V
notch after-processed.
Surface roughness: Using a surface roughness tester [Surfcom 304B,
manufactured by Tokyo Seimitsu], the surface roughness of the mirror plate
(the roughness of the metal mold=0.8s) of the orbiting scroll was
determined with a measuring length of 2.5 mm in an optional position and
the maximum height R.sub.max was recorded.
The respective components shown in Table 1 are as follows.
(A) Thermoplastic Resin
A-1: Polyphenylene sulfide resin (tradename RYTON R-6, manufactured by
Phillips Petroleum; melt viscosity at 300+ C.=2000 poises)
(B) Whisker
B-1: Potassium titanate (tradename Tismo-D101; average fiber diameter 0.3
.mu.m, tensile modulus 28,000 kgf/mm.sup.2 ; manufactured by Otsuka
Chemical Co., Ltd.)
B-2: .alpha.-Alumina whiskers (tradename Saffil; average fiber diameter 3
.mu.m, tensile modulus 49,200 kgf/mm.sup.2 ; manufactured by ICI)
(C) Heat-Resistant Fiber
C-1: Carbon fiber (tradename Besfight HTA-C6-NR, average fiber diameter 7
.mu.m, tensile modulus 24,000 kgf/mm.sup.2, fiber length 6 mm;
manufactured by Toho Rayon)
C-2: Zirconia fiber (average fiber diameter 7 .mu.m, tensile modulus 12,900
kgf/mm.sup.2, specific gravity 5.6, fiber length 6 mm; manufactured by
Hittman)
(D) Finely Divided Solid Lubricant
D-1: PTFE (tradename Fluon L150J; average particle diameter 9 .mu.m;
manufactured by Asahi Fluoropolymer)
D-2: MoS.sub.2 (tradename Molypowder-B; average particle diameter 5.0
.mu.m, manufactured by Nippon Graphite Industries)
D-3: All-aromatic polyamide (polyphenylene isophthalamide resin powder,
average particle diameter 86 .mu.m, (manufactured by Teijin Limited))
(E) Filling Agent
E-1: Brass powder
TABLE 1
______________________________________
Comparative
Example Example
Component (parts by weight)
1 2 3 4 1 2
______________________________________
Thermoplastic resin
A-1 55 70 40 40 60 63
Whisker
B-1 23 15 38 -- 33 --
B-2 -- -- -- 19 -- --
Heat-resistant fiber
C-1 15 10 10 -- -- 30
C-2 -- -- -- 18 -- --
Finely divided solid lubricant
D-1 7 5 10 6 7 7
D-2 -- -- 2 -- -- --
D-3 -- -- -- 2 -- --
Filling agent
E-1 -- -- -- 15 -- --
______________________________________
TABLE 2
______________________________________
Comparative
Characteristics of
Example Example
material 1 2 3 4 1 2
______________________________________
Specific gravity
1.67 1.54 1.91 2.24 1.72 1.49
Flexural modulus
1680 980 1820 1760 1410 1450
(kgf/mm.sup.2)
Deflexion 253 216 249 254 238 260
temperature (.degree.C.)
Sliding characteristics
Coefficient of dynamic
0.16 0.21 0.15 0.20 0.33 0.25
friction
Specific wear 0.008 0.016 0.005
0.004
0.278 0.015
(mm.sup.3 /kgf .multidot. km)
Izod impact 3.3 2.9 2.6 2.7 1.6 4.1
(kgf .multidot. cm/cm)
Surface roughness
2.8s 2.1s 1.6s 4.6s 1.2s 11.2s
______________________________________
The following is obvious from Tables 1 and 2. Thus, Comparative Example 1,
which does not contain heat-resistant fiber, is not sufficient in wear
resistance (large specific wear) and impact resistance. Furthermore, when
these parts were subjected to a field test, the scroll lap was chipped and
the amount of wear was large. In Comparative Example 2 wherein Whisker was
not used, it is evident from the surface roughness data that no mirror
surface can be obtained. Moreover, when these parts were subjected to a
field test, the compression efficiency was poor compared with the use of
parts with less surface roughness.
On the other hand, in Examples 1 to 4 wherein both the whisker and
heat-resistant fiber were used, the specific gravity was in the range of
1.3 to 2.5 and the other characteristics were also satisfactory for
practical application with a flexural modulus of not less than 800
kgf/mm.sup.2, a deflexion temperature of not less than 180.degree. C., a
coefficient of dynamic friction, which is representative of sliding
characteristic, of not more than 0.25, and a specific wear, representative
of wear resistance, of not more than 0.05 mm.sup.3 /kgf.km, and an impact
resistance of not less than 2.5 kgf.cm/cm. The surface roughness was also
not more than 5.0s and, therefore, mere injection-molding of this resin
composition (without machining) provides a mirror surface. The field test
using an assembled scroll compressor also demonstrated that these parts
were fully serviceable.
An example of the scroll compressor assembled using the fixed and orbiting
scrolls molded from the resin composition of this invention is shown in
FIGS. 1 and 2.
FIG. 1 is a longitudinal sectional elevation view showing the above scroll
compressor and FIG. 2 is a sectional view of the same scroll compressor as
taken along the line I--I' of FIG. 1.
In FIGS. 1 and 2, the parts or members represented by respective numerals
are as follows.
1: Fixed scroll
(1a: mirror plate, 1b: scroll lap)
2: Orbiting scroll
(2a: mirror plate, 2b: scroll lap)
3 and 3': Drive shaft
4: Balance weight
5 and 5': Bearing
6: Eccentric oiling port
7: Frame
8: Oldham coupling (anti-spinning mechanism)
9: Suction line
10: Discharge port
11: Intermediate pressure chamber
12: Closed housing
13: Motor
14: Lubricating oil
15: Discharge line
16: Gas pocket
In the scroll compressor shown in FIGS. 1 and 2, a fixed scroll (1) having
a mirror plate (1a) and a scroll lap (1b) perpendicular to said mirror
plate and an orbiting scroll (2) having a mirror plate (2a) and a fixed
scroll lap (2b) perpendicular to said mirror plate were manufactured by
injection-molding of the composition of this invention. As a drive shaft
(3) is driven by an electric motor (13), a shaft (3') in contact with, for
example, an oil-impregnated sintered metal bearing (5') of the orbiting
scroll (2) causes the orbiting scroll (2) to undergo gyration. As a
result, a space (16) defined by respective laps (2b) and (1b) and mirror
plates (2a) and (1a) of the orbiting scroll (2) and fixed scroll (1) is
reduced in volume towards the center. Therefore, the gas introduced from a
suction line (9) is compressed and discharged from a discharge port (10)
while the gas in a top space (20) within a closed housing (12) flows to a
bottom space (24) through a passageway (22) and is exhausted from the
closed housing (12) via a discharge line (15).
EXAMPLE 5
Using the resin composition of Example 1 and, as an insert, an iron core
(FC25), a drive shaft for the orbiting scroll was injection-molded. This
drive shaft was a part such as the member indicated by reference numeral
(3) or (3') in FIG. 1.
The resulting drive shaft was very satisfactory in surface smoothness and
dimensional accuracy and, as found by a field trial, was also satisfactory
in wear resistance. Compared with the conventional metallic drive shaft,
it was operable without oil lubrication in the case where an internally
lubricated sintered metal bearing is used. Moreover, it was found that
when the shaft was driven with a motor at 50 Hz and 130-180 V, the noise
was lower by 2 to 5 dB.
EXAMPLES 6 to 10
Resin compositions (pellets) were prepared in the same manner as Examples 1
to 4 except that the respective components shown below in Table 3 were
used in the amounts (parts by weight) indicated in Table 3. The respective
compositions were injection-molded into fixed scroll and ASTM specimens,
which were then evaluated as described hereinbefore. The results are shown
in Table 4.
The respective components shown in Table 3 were as follows.
(A) Thermoplastic Resin
A-2: Polyetheretherketone (tradename Victrex PEEK 450G; manufactured by
ICI)
A-3: All-aromatic polyester (tradename Vektra-A950; manufactured by
Celanese)
A-4: Nylon-4,6 (tradename Stanyl; manufactured by DSM)
A-5: Polyethersulfone (tradename Victrex PES 4100G; manufactured by ICI)
A-6: Polyetherimide (tradename Ultem #1010; manufactured by GE)
(B) Whiskers
B-3: SiC whiskers (tradename Tokamax; average fiber diameter 0.5 .mu.m,
tensile modulus 41,000 kgf/mm.sup.2); manufactured by Tokai Carbon)
B-4: Si .sub.3 N.sub.4 whisker average fiber diameter 0.5 .mu.m, tensile
modulus 38,700 kgf/mm.sup.2 ; manufactured by Tateho Chemical)
(C) Heat-Resistant Fiber
C-3: SiC fiber (tradename Nikalon; average fiber diameter 12 .mu.m, tensile
modulus 20,000 kgf/mm.sup.2, fiber length 3 mm, manufactured by Nippon
Carbon)
C-4: Glass fiber (tradename ECS-03-T24; average fiber diameter 10 .mu.m,
tensile modulus 7,700 kgf/mm.sup.2, fiber length 3 mm; manufactured by
Nippon Electric Glass)
C-5: Aramid fiber (tradename Technora T-320; average fiber diameter 12
.mu.m, tensile modulus 7,100 kgf/mm.sup.2, fiber length 3 mm, manufactured
by Teijin Limited)
C-6: Alumina fiber (spinel-form, Al.sub.2 O.sub.3 /SiO.sub.2 =85/15,
average fiber diameter 9 .mu.m, tensile modulus 25,000 kgf/mm.sup.2, fiber
length 3 mm; manufactured by Sumitomo Chemical)
(D) Finely Divided Solid Lubricant
D-4: BN (tradename Sho-BN UHP; average particle diameter 2 .mu.m;
manufactured by Showa Denko)
D-5: Ultra-high molecular weight polyethylene [tradename Hizex Million
microfine powder; average particle diameter 50 .mu.m, average molecular
weight 3 million; manufactured by Mitsui Petrochemical Industries)
D-6: High density polyethylene (tradename Hizex 5000; average particle
diameter 30 .mu.m, average molecular weight 70 thousand; manufactured by
Mitsui Petrochemical Industries)
D-7: Graphite (tradename ACP-1000; average particle diameter 6 .mu.m, fixed
carbon 99.5%; manufactured by Nippon Graphite Industries)
TABLE 3
______________________________________
Example
Component (parts by weight)
6 7 8 9 10
______________________________________
A-2 60 -- -- -- --
A-3 -- 50 -- -- --
A-4 -- -- 60 -- --
A-5 -- -- -- 60 --
A-6 -- -- -- -- 63
B-1 -- 30 25 -- 20
B-3 20 -- -- -- --
B-4 -- -- -- 20 --
C-1 10 -- -- 10 --
C-3 -- 13 -- -- --
C-4 -- -- 10 -- --
C-5 -- -- -- 3 --
C-6 -- -- -- -- 10
D-1 7 -- -- 7 --
D-4 3 -- -- -- --
D-5 -- 7 -- -- --
D-6 -- -- 5 -- 4
D-7 -- -- -- -- 3
______________________________________
TABLE 4
______________________________________
Example
Characteristics of material
6 7 8 9 10
______________________________________
Specific gravity
1.60 1.72 1.48 1.64 1.53
Flexural modulus (kgf/mm.sup.2)
1350 1890 830 1230 970
Deflexion temperature (.degree.C.)
>260 252 >260 212 210
Sliding characteristics
Coefficient of dynamic
0.18 0.22 0.19 0.18 0.18
friction
Specific wear 0.005 0.023 0.003 0.038
0.042
(mm.sup.3 /kgf .multidot. km)
Izod impact (kgf .multidot. cm/cm)
4.5 2.7 6.3 3.7 3.2
Surface roughness
3.2s 4.7s 3.4s 4.5s 3.8s
______________________________________
It will be apparent from Table 4 that the scroll compressor parts
injection-molded from the resin composition of this invention have a
specific gravity in the range of 1.3 to 2.5, a flexural modulus of not
less than 800 kgf/mm.sup.2, a deflexion temperature of not less than
180.degree. C., a sliding characteristic, in terms of coefficient of
dynamic friction, of not more than 0.25, a wear resistance, in terms of
specific wear, of not more than 0.05 mm.sup.3 /kgf.km, an impact
resistance of not less than 2.5 kgf.cm/cm and a surface roughness of not
more than 5.0s, thus being sufficiently capable of replacing metallic
parts.
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